Kemal Ataturk was the great bringer of Turkish secularism. Like later Muslim dictators in the Middle East, he regarded imam-driven political Islam as competition to be crushed. Nasser, both Assads, Saddam, & Gaddafi followed his example.
But Ataturk sowed mass murder among Christians in Asia Minor. He was part of the operation to exterminate Christian Armenians in 1915, and the entire Greek Christian community in the new Turkey was either wiped out or forced to flee.
Ataturk did not really bring secularism to Turkey but a nationalized Turkish new Islam to go with a nationalized ethnicity. On the face of it it seems better but ironically it was also genocidal because it was based on an exclusive nationalist religious identity.